He needs no introduction... he hates the Saiyan Race, is malicious and mean, and his families' names relate to Cold things :P.
That's right it's Frieza!
Mecha Frieza appeared at the beginning of the Cell Saga in which he arrived to earth after being defeated by Goku on Planet Namek. Coincidentally at the same time the newest Z Fighter Trunks also arrived on the scene.
When Frieza threatens Earths' destruction he is quickly ended by Trunks who slices him in half. He is no match for the new Saiyan.